1. Field of the invention
This invention relates generally to the field of archery apparatus, especially to archery bows, and more particularly, to apparatus for assisting in the stringing and unstringing of compound archery bows.
2. Background Discussion
Bows and arrows have, for centuries, been used for hunting, sport and warfare. Although now seldom used for warfare (but reportedly still used in some commando operations), bows and arrows are still widely used for sport--including Olympic competition--and hunting. Over the centuries that bows have been used, bows have been constructed of numerous materials and in various shapes. Bows have, for example, been constructed of wood, horn, sinew, steel, and fiber-reinforced compositions, such as fiberglass or graphite-reinforced plastic. Bow shapes have included the famed, singly-curved, English long-bows and the short, recurved horn bows used by Gengis Kahn's horsemen. Included are cross-bows which appeared on the scene in the middle ages.
However, within about the last decade, so-called compound bows have virtually obsoleted conventional bows for both sport and hunting. Compound bows are typically constructed having pulleys at the free ends of the limbs, and usually other pulleys or cams mounted elsewhere on the bow. A ca is strung over the pulleys, usually in a criss-cross pattern, with a conventional bow string generally being attached between ends of the cable. The configuration and location of the pulleys and the routing of the cable are such that when the bow is bent (by pulling on the bow string in a normal manner) almost to a full draw, the pulling force (that is, the drawing force) unloads so that the amount of pulling force required to keep the bow fully drawn is less than that required to draw the bow to the unloading position. As an illustration, a normal "55 pound" bow requires about 55 pounds of drawing force to fully draw the bow; the same amount of force is required to keep the bow drawn. If the arrow is not immediately released, the drawing arm becomes quickly fatigued and muscle spasms may result, causing the arrow, when released, to miss whatever was being aimed at. In contrast, a "55 pound" compound bow still requires about 55 pounds of pulling force to draw the bow to the unloading point, but thereafter may, for example, require only about 25 pounds to keep the bow fully drawn. When the arrow is released, however, the bow acts on the arrow like a conventional 55 pound bow. Consequently, compound bows can be kept fully drawn much more easily than conventional bows of like drawing force, making them more suitable for target shooting and especially more applicable for bow hunting. On the other hand, compound bows can be made with higher drawing "weights" than conventional bows because of the drawing force unloading when the bow is nearly fully drawn--in this regard, it is easier to draw a bow than it is to hold it in the fully drawn condition. It should also be noted that the drawing force on many, if not most, compound bows can be adjustably varied by rerouting the cable over other pulleys or by pivotally adjusting pulley positions--such varying of drawing power is generally not possible for conventional bows.
A related advantage of compound bows is that such bows are typically made significantly shorter in length than conventional long-bows of similar or even lower drawing force. This increases the convenience of carrying the bows in vehicles and in the brush for bow hunting. In this regard, compound bows are constructed having relatively short limbs, each of which is fastened at one end to a rigid, elongate central frame that may be constructed of metal and which is usually fashioned with a "pistol-grip" type holding region.
Although not always easy to do, long bows can usually be strung and unstrung manually without any mechanical assist being required, typically by the well-known "step-through" method in which a lower end of the bow is braced against one of the user's insteps while the bow is held in the center with one hand--the other hand being used to apply sufficient pressure to the upper bow end to enable the string to be nocked or un-nocked from the upper bow end. However, because of the stiffness of compound bow limbs, the stringing and unstringing of such bows is very difficult without some kind on mechanical assist. Moreover, it is often necessary to apply pressure to the ends of the limbs in order to replace broken cables or pulleys or make other repairs.
To this end, various types of mechanisms for stringing compound bows are disclosed, for example, in U.S. Pat. Nos. 4,050,137; 4,074,409; 4,077,385; 4,195,397; 4,291,452; and 4,846,142 issued respectively to John A. Carlson, Jimmie T. Smith, Bert E. Fredrickson, Charles A. Saunders, Archie E. Whitman et al, and Richard Tone.
The Carlson '173 patent discloses an auxiliary cable which clips onto the compound bow cable above and below the string holders at ends of the bow cable, When the auxiliary cable is drawn instead of the bow sting, tension on the bow sting is released and the string may be replaced. It is, however, apparent that a second person is then needed to remove and replace the bow string since the auxiliary cable must remain drawn. Since the disclosed mechanism is hooked onto the bow cable it cannot be used for replacing the bow cable or to replace pulleys over which the bow cable passes. The mechanism disclosed in the Fredrickson '385 patent is similar to that disclosed in the Carlson '173 patent except that ends of the auxiliary cable are attached to distal ends of the bow limbs. Tension on the bow string is released, for replacement of the string, by drawing on the auxiliary cable. Again, a second person is required to remove and replace the bow string while the auxiliary cable is drawn. Moreover, tension on the bow cable is relaxed only while the auxiliary cable is drawn, making the disclosed mechanism inappropriate for replacement of the bow cable or pulleys.
The mechanism disclosed in the Tome '142 patent comprises an auxiliary cable, the retainer ends of which are inserted in fork-ends of the bow limbs when the existing bow string is drawn and the distal ends of the bow limbs are bent toward one another. When the bow string is then slowly released, the auxiliary cable retains the bow limbs in the bent condition, thereby enabling the bow string to go slack so that it can be removed. This mechanism also requires a second person to install the auxiliary cable when the bow string is drawn, although this could be a dangerous operation if the bow string should break. The auxiliary cable is removed by drawing the installed bow string until the auxiliary cable goes slack and the ends thereof can be removed from the fork ends of the bow limbs.
The mechanism disclosed in the Smith '409 patent includes an auxiliary cord which connects to the bow cable above and below the string attachment elements, the cord being slideably connected by an auxiliary pulley to the bow cable toward one end. One end of an elongate handle is attached to one end of the auxiliary cord near the auxiliary pulley to enable the cord to be pulled generally parallel to the bow string to thereby pull the distal ends of the bow limbs toward one another until the bow string is slackened sufficiently so that it can be removed or sufficiently so that a bow string can be installed. The other end of the handle has an aperture through which the auxiliary cord passes so that the handle slides along the cord. When the handle is pulled to tension the auxiliary cord and is then released the tension in the cord pivots the handle so that the handle retains the cord in the tensioned condition. It appears that this might be dangerous to operate since the operator's hand might get caught between the handle and the cord as the handle is being released to retain the cord in its tensioned condition. Also it appears that it would be a difficult operation to repivot the handle to release the cord after a bow string has been installed onto the bow cable.
The Saunders '397 patent discloses an apparatus very similar to the Smith apparatus except that a slack remover is installed on the auxiliary cord.
The apparatus disclosed in the Whitman, Sr. et al. '452 patent comprises an auxiliary cable end regions of which attach to ends of the bow cable adjacent to the bo string attachment elements. The auxiliary cable is tensioned to pull the distal ends of the bow limbs toward one another to slacken the bow string by an over-center locking lever near the center of the auxiliary cable. It appears that operation of the lever would be very difficult and as it is snapped into the over-center locking position there would be a great danger of the operator's hand being caught in the lever mechanism. Moreover, after a bow string in installed, the releasing of the over-center locking mechanism would appear be very difficult and the sudden release of tension in the auxiliary cable could cause the installed bow string to snap and/or cause damage to the bow's cable mechanism.
Because of the above-mentioned deficiencies or difficulties with known, existing apparatus or auxiliary mechanisms for enabling the removing and installing of bow strings on compound bows, improvements to such apparatus and mechanisms is needed and it is the objective of the present invention to provide such improvements so as to make the restringing operation of compound bows easier and safer--both to the operator and to the bow itself.